Small, cheap smart-tag devices that are printed as digital circuits in rolls like newspapers could help kickstart the wireless payment industry. The devices, known as rectennas, combine a rectifier - which converts current from AC to DC - with an antenna, and can harness power directly from radio waves given off by a mobile phone.

Developed by a team at Sunchon National University and Paru Printed Electronics Research Institute in South Korea, the rectenna is based on Near Frequency Communication (NFC) technology, an update to the more familiar RFID standard found in London Underground's Oyster ticketing system, for example.

NFC chips can be used to tag many of the same things RFID chips can, from pets to luggage to boxes in a warehouse. The killer app is likely to be contactless payment, where payments are made by waving a reader in a phone over an NFC price tag. Though this technology has been touted for a few years now - and worldwide payments by NFC-enabled phones are predicted to reach $50 billion - its uptake has been slow, largely due to the costs of installing millions of devices. The new rectennas would bring the cost down to as little as 1 penny per unit, the team says.

But the key advantage of NFC is that it allows two-way communication. An RFID tag can only be read, but with NFC devices information can be sent back and forth between tag and reader.

The back-and-forth exchange of information between a reader and a cheap printed tag would also make peer-to-peer or local Bluetooth-like communication possible. [Nanotechnology]